In general, there have been two types of plate for a lead storage battery, one of which is of paste type and the other of which is of clad type.
The paste type plate is disposed between adjacent sets of a glass fiber mat and an insulated separator with a slight pressure applied to a group of plates. Although such a plate can be easily and inexpensively produced, it disadvantageously has a shorter life because active material for a positive plate falls out of the plate grid as charging and discharging are repeated, with the result that the adjacent plates are electrically shorted. On the other hand, the clad type plate has a longer life, but the steps of producing it, such as forming a clad tube and filling the clad tube with active material are complicated so that the cost for producing the plate is ineconomically higher.
Of late, there has been proposed a plate for a lead storage battery which has an advantage of the paste type plate and that of the clad type plate in combination (see U.S. Pat. No. 4,055,711). The proposed plate comprises a plate grid of lead or lead alloy filled with pasted active material and a pair of holders of porous insulated material provided on both sides of the plate grid. A pair of porous holders are provided with a plurality of longitudinal ribs which are butted against each other or bonded to latitudinal members of the plate grid. Thus, it will be noted that troublesome operations of bonding the longitudinal ribs to the holders and of butting them against each other or bonding them to the plate grid have to be done, which causes the effectiveness of operations to be lower and also the operations to be prevented from being automatically done.